• Our booking engine at tickets.railforums.co.uk (powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!

Shortest section of single track

Status
Not open for further replies.
Joined
31 Aug 2019
Messages
341
Location
IW
I see. It seems youre right then, the single line isnt into the platforms.
Its only until a train is some 40 - 80 meters past those points...which is about what?

Its all self loading these days., it all comes nicely wrapped up in some kind of clean plastic so you dont get your hands dirty and even disposes of itself when done!
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

Belperpete

Established Member
Joined
17 Aug 2018
Messages
1,575
Bi-directional is the formal term for a line over which trains can be signalled in either direction, reversible (a less formal term) is bi-directional but normally worked in only one direction.
I think that "bi-directional" is a 'relatively' modern term. I have looked at a copy of my Southern Region "Yellow Book" dating back to the late 1970s, and it includes information about "reversible lines" but has no mention whatsoever of "bi-directional" signalling.

The term "bi-directional" came into vogue in the late 80s, when what would traditionally have been unidirectional up and down main-lines were provided with extra crossovers and reversible signalling, usually as part of a major resignalling project, to avoid hand-signalling when one of the tracks was closed. With "bi-di", it is usual for one track to be used by up trains and the other by down trains, and hence they are still referred to as the UP and DOWN lines. A form of simplified bi-directional signalling (SIMBIDS) came briefly into vogue, in an attempt to minimise the extra costs involved in full bi-di.

So I have always regarded the term "reversible" to refer to any running line that can be used equally for both up and down trains, whereas the term bi-directional refers to a pair of running lines that are both reversibly-signalled.

I can recall reading somewhere (one of OS Nock's books, I think), that the first truly fully-reversible signalling on a running line was installed between East Croydon and Gloucester Road, where a third, reversible line was provided in addition to the usual up and down lines, being used for up trains in the morning rush and down trains in the evening - this reportedly caused a lot of controversy at the time as it was effectively a single line without tokens, and the HMRI took some persuading to approve it. Lines that are used equally by up and down trains, with no predominant direction of travel, were traditionally named "REVERSIBLE", so on a three-track main-line you would have the UP, the DOWN and the REVERSIBLE. I can't recall ever seeing the term "Down and Up" to denote a reversible line - I suspect that this is a regional thing. However, I am sure I have seen lines called the "Up Reversible" and "Down Reversible"!
 
Joined
31 Aug 2019
Messages
341
Location
IW
Excerpt from the LNW sectional appendix.

Line-types.jpg
 
Status
Not open for further replies.

Top